Nature and Measurement of Deposit Layers in Paper Machine Loops, 2007 TAPPI Papermakers and PIMA International Leadership Conference

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This paper describes the mechanism of deposit formation in paper machine loops, from the initiating layer to the bulkdeposit. A case where ASA sizing was the primary cause of the deposit is presented, and the role of bacteria that morphologically looks like Deinococcus spp is discussed. Two real cases where the Deinococcus spp like bacteria shows their capability as a primary colonizer can be seen, measured with steel coupons placed directly in the process. The methodic used to analyze the deposits is based on stainless steel coupons, placed in Situ in the loops. The coupons are then fixed onsite, and analyzed by the use of novel microscopy methods like Scanning Electron microscopy (SEM) with Energy Dispersive Xray analysis (EDX), and Epifluorescent microscopy (EP). Further presented is also the impact of the raw water quality where the analysisis done by the coupon method, and with traditional analytical methods like microbiological plaiting and light microscopy. The conclusions drawn from these measurements shows that one has to take the raw water treatment serious, to make sure no impact on the runnability and the quality occurs. To be able to take counter actions in time, a nonline monitor was developed where the materials are equal to the materials in the machine loops. Data on the thickness, as well as the stability and the pace of growth can be retrieved, and gives the papermaker information about the structure of the deposit so that counter actions can be taken before any economical losses occur.